Common Stock (Stock Repurchase Program) (Details) (USD $) In Thousands, except Share data	0 Months Ended			3 Months Ended	6 Months Ended	152 Months Ended
	Jun. 30, 2011	Mar. 21, 2011		Jun. 30, 2011	Jun. 30, 2011	Jun. 30, 2011		Dec. 31, 2010
Common Stock
Shares repurchased				323,838	910,749	23,534,478	[1]
Cost, including commission (in thousands)				$ 9,645	$ 26,320	$ 363,459	[1]
2010 Plan balance at December 31, 2010								676,271
2011 Plan repurchase shares authorized		2,500,000	[2]
Total remaining shares available for repurchase at June 30, 2011	2,265,522

[1] Represents repurchased shares and cost since inception of the stock repurchase program in 1999.

[2] On March 21, 2011, the Board of Directors authorized an additional repurchase of the Company's common stock (the "2011 Plan").